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package bjc.utils.parserutils;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
import java.util.function.BiConsumer;
import java.util.function.Consumer;
import bjc.utils.data.Pair;
import bjc.utils.funcdata.FunctionalStringTokenizer;
/**
* This class parses a rules based config file, and uses it to drive a
* provided set of actions
*
* @author ben
*
* @param <E>The
* type of the state object to use
*/
public class RuleBasedConfigReader<E> {
private BiConsumer<FunctionalStringTokenizer, Pair<String, E>> startRule;
private BiConsumer<FunctionalStringTokenizer, E> continueRule;
private Consumer<E> endRule;
private Map<String, BiConsumer<FunctionalStringTokenizer, E>> pragmas;
/**
* Create a new rule-based config reader
*
* @param startRule
* The action to fire when starting a rule
* @param continueRule
* The action to fire when continuing a rule
* @param endRule
* The action to fire when ending a rule
*/
public RuleBasedConfigReader(
BiConsumer<FunctionalStringTokenizer, Pair<String, E>> startRule,
BiConsumer<FunctionalStringTokenizer, E> continueRule,
Consumer<E> endRule) {
this.startRule = startRule;
this.continueRule = continueRule;
this.endRule = endRule;
this.pragmas = new HashMap<>();
}
public void addPragma(String pragName,
BiConsumer<FunctionalStringTokenizer, E> pragAct) {
pragmas.put(pragName, pragAct);
}
public E fromStream(InputStream is, E initState) {
Scanner scn = new Scanner(is);
E stat = initState;
while (scn.hasNextLine()) {
String ln = scn.nextLine();
if (ln.equals("")) {
endRule.accept(stat);
continue;
} else if (ln.startsWith("\t")) {
continueRule.accept(new FunctionalStringTokenizer(
ln.substring(1), " "), stat);
} else {
FunctionalStringTokenizer stk = new FunctionalStringTokenizer(
ln, " ");
String nxtToken = stk.nextToken();
if (nxtToken.equals("#")) {
// Do nothing, this is a comment
} else if (nxtToken.equals("pragma")) {
String tk = stk.nextToken();
pragmas.getOrDefault(tk, (strk, ras) -> {
throw new UnknownPragmaException(
"Unknown pragma " + tk);
}).accept(stk, stat);
} else {
startRule.accept(stk,
new Pair<String, E>(nxtToken, stat));
}
}
}
scn.close();
return stat;
}
public void setContinueRule(
BiConsumer<FunctionalStringTokenizer, E> continueRule) {
this.continueRule = continueRule;
}
public void setEndRule(Consumer<E> endRule) {
this.endRule = endRule;
}
public void setStartRule(
BiConsumer<FunctionalStringTokenizer, Pair<String, E>> startRule) {
this.startRule = startRule;
}
}
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